multiplies
class template
<functional>
template <class T> struct multiplies;
Multiplication function object class
This class defines function objects for the multiplication arithmetic operation.
Generically, function objects are instances of a class with member function operator() defined. This member function allows the object to be used with the same syntax as a regular function call, and therefore it can be used in templates instead of a pointer to a function.
multiplies has its operator() member defined such that it returns the product of its two arguments.
This class is derived from binary_function and is defined as:
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template <class T> struct multiplies : binary_function <T,T,T> {
T operator() (const T& x, const T& y) const
{return x*y;}
};
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Objects of this class can be used with some standard algorithms such as transform or accumulate.
Members
- T operator() (const T& x, const T& y)
- Member function returning the product of its two arguments (x*y).
Example
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// factorials (multiplies example)
#include <iostream>
#include <functional>
#include <numeric>
using namespace std;
int main () {
int numbers[9];
int factorials[9];
for (int i=0;i<9;i++) numbers[i]=i+1;
partial_sum ( numbers, numbers+9, factorials, multiplies<int>() );
for (int i=0; i<9; i++)
cout << numbers[i] << "! is " << factorials[i] << "\n";
return 0;
}
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Output:
1! is 1
2! is 2
3! is 6
4! is 24
5! is 120
6! is 720
7! is 5040
8! is 40320
9! is 362880
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See also
| plus | Addition function object class (class template) |
| minus | Subtraction function object class (class template) |
| divides | Division function object class (class template) |
| modulus | Modulus function object class (class template) |
| negate | Negative function object class (class template) |
| equal_to | Function object class for equality comparison (class template) |
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